http://nopr.niscair.res.in/handle/123456789/10029 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/10037 Title: EDXRF determination of Dy, Eu, Gd and Sm in aqueous solutions <br/> <br/>Authors: Porwal, N K; Natarajan, V; Kumar, Mithlesh; Rajeswari, B; Kulkarni, M J; Bhide, M K; Dhawale, B A; Godbole, S V <br/> <br/>Abstract: An EDXRF technique for the determination of four important rare earth impurities, viz., Eu, Dy, Sm and Gd, at 20-1000 <img src='/image/spc_char/micro.gif' border=0>g/ml in aqueous medium as well as in the presence of uranium has been reported. The conditions have been optimized for the simultaneous determination of these elements. The limits of detection for the analytes in aqueous solutions are determined to be 20 <img src='/image/spc_char/micro.gif' border=0>g/ml. In order to achieve lower limits of detection, a novel method based on polyvinyl alcohol films containing these rare earths has been established. Four uranium oxide samples have been analysed by EDXRF as well as inductively coupled plasma–atomic emission spectrometry after chemical separation of uranium. The results are in good agreement. <br/> <br/>Page(s): 1052-1055 http://nopr.niscair.res.in/handle/123456789/10036 Title: Synthesis and characterization of gallosilicate halide sodalites using organic solvent <br/> <br/>Authors: Borhade, A V; Wakchaure, S G <br/> <br/>Abstract: The crystallization of gallosilicate sodalite containing halides (Cl, Br and I) in 30% ethanol have been investigated at low temperature (373 K) using one pot synthesis method. X-ray powder diffraction, IR, FAR IR, ²⁹Si and ²³Na MAS NMR, SEM and thermogravimetric data are used to characterize these sodalites. The crystal structures show cubic symmetry in a space group P3n. The crystal structures have been refined by Rietveld refinement method. The unit cell parameter, <i>a</i> = 8.9502, 8.9986 and 9.0779 Å and the corresponding Ga-O-Si angle are found to be 134.453, 135.252 and 136.887^o for chloro, bromo and iodo sodalite respectively. The MAS NMR data confirm the alternating Ga and Si ordering of sodalite framework. TGA analysis shows stability of guest anions in the sodalite framework. <br/> <br/>Page(s): 1047-1051 http://nopr.niscair.res.in/handle/123456789/10035 Title: Catalytic activity of enzyme in water/organic cosolvent mixtures for the hydrolysis of <i style="">p</i>-nitrophenyl acetate and <i style="">p</i>-nitrophenyl benzoate <br/> <br/>Authors: Verma, Santosh Kumar; Ghosh, Kallol K <br/> <br/>Abstract: The dependence of the catalytic activities of α-chymotrypsin on the concentration of organic cosolvents (acetonitrile, dimethyl sulfoxide, dimethyl formamide, ethylene glycol, methanol, ethanol, propan-2-ol and <i style="">tert</i>-butanol) in mixed aqueous media has been studied towards hydrolysis of <i style="">p</i>-nitrophenyl acetate and <i style="">p</i>-nitrophenyl benzoate using cetyltriphenylphosphonium bromide surfactant at <i style="">p</i>H 7.75. The temperature dependence hydrolysis of PNPA and PNPB catalyzed by α-chymotrypsin has also been reported. Under all the conditions employed, the reaction follows a Michaelis-Menten mechanism. The organic solvent influences the <i style="">k</i>_catand <i style="">K</i>_M. The effect of polarity of solvent on the catalytic activity has been discussed. It is observed that the catalytic efficiency of α-chymotrypsin is enhanced in aqueous-organic media. Possible mechanism of micellar enzymology and the effect of organic co-solvents have been discussed. <br/> <br/>Page(s): 1041-1046 http://nopr.niscair.res.in/handle/123456789/10034 Title: Solar photocatalytic degradation of Acid Black 1 with ZnO<b></b> <br/> <br/>Authors: B Krishnakumar, M Swaminathan <br/> <br/>Abstract: The degradation of an azo dye, Acid Black 1 (AB 1) with ZnO as photocatalyst using natural solar light in aqueous solution has been investigated under different conditions. The degradation is more with solar/ZnO process than with solar/TiO₂-P25 process at <i>p</i>H 9. The influence of operational parameters such as the amount of photocatalyst, dye concentration and initial <i style="">p</i>H on photodegradation by ZnO has been analyzed. The degradation of AB 1 follows pseudo-first order kinetics according to the Langmuir-Hinshelwood model. The intermediates formed during the photodegradation have been identified by GC-MS analysis. The mineralization of AB 1 has been confirmed by cyclic voltammetric and COD measurements. <br/> <br/>Page(s): 1035-1040